European Patent Application EP-A-0 124 241 discloses a microscope having an automatic focus device. The microscope encompasses a storage device for saving data from the objectives that are being used in the microscope. Also provided is a control device that monitors and controls the various microscope functions. Another of the tasks of the control device is motion of the microscope stage (also called the focusing stage). Provided as the image acquisition device is a CCD element which receives an image from the particular selected objective and, together with a calculation unit, determines the optimum focus position based on contrast. The objective data of the objective currently in use must be taken into account in determining the optimum degree of sharpness. The system disclosed here is not configured to determine contrast values in the context of a microscope stage moved continuously in the Z direction.
A problem in automatic focus adjustment for microscopes is that the time for achieving the optimum focus position is too long.